As my previous patent describes, conferencing is the capability of coupling information signals among three or more users in a communications system--typically in voice format, but also for data, video, facsimile and like nonvoice signals. As is there set forth, problems existed with prior arrangements dealing with compressed information signals in that degradation resulted in signal quality due to the tandem serial connection of coders and decoders to respectively compress and decompress the various information signals. In accordance with that invention, a conferencing arrangement was described which detected whether there were one or more conferees speaking, for example, on a line at any one time; when there was only one conferee speaking, a summer in the conference bridge unit was bypassed, and that conferee's signal was then broadcast directly to all other conferees; when there were more than one conferee speaking, the signals of those that were speaking were first routed to an associated speech decoder, decompressed, summed, and then recompressed again before being broadcast. As set forth in my issued patent, a conferencing arrangement operating in that manner reduced signal degradation associated with the tandeming of the signal coders and decoders, and permitted the sharing of a smaller number of signal decoders amongst a larger number of conferees.
Even with this, however, it has been determined that improved conferencing could be had if the arrangement employed allowed a degree of volume control for individual conferees, and/or for automatic gain control for all conferees speaking--whether or not at one time. However, the techniques employed in the prior art for volume control in systems utilizing compression algorithms to minimize signal bandwidth operate to degrade the quality of the signal due to the signal loss in each single encoder and decoder in the serial connection as well.